1. Field of the Invention
The present invention generally relates to vehicle sound emitting technology for informing a person in an area surrounding of the vehicle that the vehicle is moving, or is about to move, in an advancement direction, e.g., forward or rearward. More specifically, the present invention relates to a vehicle notification sound emitting apparatus that emits a notification sound to inform people of the existence of the vehicle.
2. Background Information
Some vehicles have a very quiet operating sound and/or moving sound (including a vehicle equipped with an internal combustion engine). For example, an electric powered vehicle such as an electric car configured to be electrically driven (EV drive) using only an electric motor is typically very quiet while operating and/or moving. Also for example, a hybrid vehicle having an electric drive mode (EV mode) in which the vehicle is driven solely with an electric motor is typically very quiet while operating and/or moving. In such very quiet vehicles, the operating sound and/or moving sound (vehicle information) such as the existence of the vehicle, an intent of a driver as indicated by a gear shift or other operation, an advancement direction of the vehicle (forward or reverse), a vehicle speed and/or other traveling condition of the vehicle are often not perceivable to a person in a surrounding area of the vehicle by emitting a notification sound to the outside of the vehicle. Thus, while typically it is desirable for the occupants of the vehicle to have a very vehicle, there are times when it is desirable for the vehicle convey the existence of the vehicle to a person in a surrounding area of the vehicle by emitting an notification sound to the outside of the vehicle.
Among the vehicle information mentioned above, technology has been proposed for emitting a movement notification sound to inform a person in an outside area surrounding a vehicle that the vehicle is moving in a forward direction (i.e., an advancement direction). For example, conventional technology is disclosed in Japanese Laid-Open Patent Publication No. 11-208307 in which a movement notification sound is emitted to indicate movement of the vehicle in a forward direction (i.e., an advancement direction).
In the conventional technology, when an ignition switch is turned ON and the vehicle is put into a drivable state, the apparatus detects that the ignition switch is ON and the vehicle is in a drivable state and emits a notification sound to inform a person in an outside area surrounding the vehicle regarding forward movement of the vehicle. Also in the conventional notification technology, the notification sound is emitted from the time the vehicle is put into a drivable state. In other words, a person in an outside area surrounding the vehicle can be informed of the vehicle's forward movement by a notification sound that is emitted before a movement start operation is performed after a movement start preparation operation is completed, i.e., before the vehicle actually starts moving forward.
Another example conventional movement notification sound technology is disclosed in Japanese Laid-Open Patent Publication No. 2005-343360 in which a notification sound emitting apparatus emits a forward movement notification sound for informing a person in a surrounding area of a vehicle that the vehicle is moving forward when the vehicle has started moving forward from a stop. A volume of the notification sound is changed between when the vehicle is starting into motion and when the vehicle is moving.